KR20110123754A - Apparatus and method for assessing vascular health - Google Patents

Abstract

Apparatus and methods using conductivity measurements to assess vascular health and to diagnose vascular conditions are disclosed. An exemplary method includes performing a terminal first conductivity measurement at a first height; Performing a terminal second conductivity measurement at a second height; And comparing the first conductivity measurement with the second conductivity measurement to determine the conductivity displacement Δσ. Another example method includes maintaining the conductivity sensor adjacent to the subject for a predetermined time period; Performing a series of conductivity measurements; Determining the transient behavior of the conductivity during the time period using a series of conductivity measurements; And evaluating the vascular health of the subject using the transient habit of conductivity. Also disclosed is a conductivity sensor and platform unit for conductivity measurement.

Description

Vascular health evaluation method and apparatus {APPARATUS AND METHOD FOR ASSESSING VASCULAR HEALTH}

[Priority claim]

This application is incorporated by reference in US Patent Provisional Application No. US Patent Application No. 61 / 156,269, filed May 12, 2009. 12 / 464,431, and US Patent Application No. filed May 12, 2009. Claims priority of 12 / 464,640.

The use of conductance measurements to analyze various characteristics of human tissue specimens has been found to provide many practical advantages. For example, conductivity measurements can be used to distinguish diseased tissue from healthy tissue. Both conventional electrode methods and induction coil methods have been used to perform conductivity measurements of human tissue specimens.

Conventional electrodes for measuring the conductivity of human tissue apply an AC voltage to a specimen of interest. The current through the specimen is measured and the conductivity is calculated. In some cases, many electrodes are attached, allowing imaging of the specimen in environments where the conductivity varies spatially through the specimen.

A disadvantage of conventional electrodes is that they require direct electrical contact with the tissue specimen. This is particularly true for human tissue specimens because the stratum corneum layer of the epidermis interferes with the flow of current through the specimen, which results in variable conductivity measurements. In addition, conventional electrodes may exhibit electrode polarization, which leads to inaccurate conductivity measurements.

Induction coil methods and apparatus for measuring conductivity have used a wide variety of induction coil designs, including simple loop type coils of solenoids or a few turns of wire. Such coils can probe a human tissue specimen deeply, which allows for interference from internal organs that distort bone and / or conductivity measurements. In addition, many of these devices involve the use of expensive equipment to measure parameters related to the coil, such as complex impedance, and the measurement of conductivity, using circuitry that causes the induction coil to deviate from resonance as the coil is placed adjacent to the specimen. Make it even more difficult.

D. Haemmerich, ST Staelin, JZ Tsai, "In vivo electrical conductivity of hepatic tumors", Physiological Mesurement Vol. 24, pp. 251-260 (2003) discuss the use of conventional electrode methods to measure the electrical conductivity of liver tumors to show that abnormal or diseased tissues exhibit different electrical properties compared to healthy tissues.

"A noninvasive electromagnetic conductivity sensor for biomedical applications" by LW Hart, HW Ko, JH Meyer, DP Vasholz and RI Joseph, IEEE Transactions on Biomedical Engineering, Vol. 35, No. 12, pp. 1011-1022 (1988) discuss the use of conductivity measurements to identify the presence of edema in brain tissue.

Various methods and apparatus for assessing the health of human tissues using conductivity measurements have been developed, but no design that generally encompasses all of the desirable properties, as provided below, in accordance with the teachings of the present invention.

In one aspect of the invention, a method of determining a vascular state of an individual is disclosed. The method includes performing a first conductivity measurement of the distal end of the subject at a first height. The distal end of the individual may be an arm or a leg. After the first conductivity measurement is performed, the method includes elevating the distal end of the individual to a second height and performing a second conductivity measurement at the second height. For example, the first height may be substantially at the height of the subject's heart, or below the height of the subject's heart, and the second height may be above the subject's heart. The method further includes comparing the first conductivity measurement with the second conductivity measurement to determine the conductivity displacement Δσ of the tip in response to the height variation of the tip. The conductivity displacement Δσ can be used to determine the vessel state of the subject.

In a variation of this particular aspect of the invention, the conductivity displacement Δσ may be used to determine whether a particular individual has peripheral arterial disease. In another variation of this particular aspect of the invention, the conductivity displacement Δσ can be used to monitor the warming of the patient, monitor the circulatory shock, and / or determine whether the subject has venous or arterial occlusion.

In another variation of this particular aspect of the invention, the method may further comprise performing a blood pressure measurement of the subject, such as, for example, diastolic blood pressure measurement and systolic blood pressure measurement. Blood pressure measurements can be used in conjunction with the conductivity displacement Δσ to determine the vessel state of the subject.

In still another variation of this particular aspect of the invention, the first and second conductivity measurements can be performed with a conductivity sensor including an induction coil. The induction coil can be configured to probe the specimen to a depth of up to approximately 15 mm below the subject's skin. In this particular aspect of the invention, the induction coil comprises a first conductive element helically facing outwardly around the outside and a second conductive element operably connected to the first conductive element. The second conductive elements can be staggered inwardly spirally about the outside relative to the first conductive element. In another particular aspect of the invention, the induction coil may be part of a resistive element, a capacitive element, and a reactance circuit comprising the induction coil connected in parallel. The conductivity sensor may include a control circuit configured to drive the reactance circuit to resonate when the induction coil is measuring the conductivity of the distal end.

Another aspect of the invention relates to a method of assessing the health of a vascular system of a subject. The method includes performing a first conductivity measurement of the subject and causing the subject's vascular system to be stimulated. For example, in certain embodiments of the invention, the vascular system is stimulated by subjecting the subject to active movement. As used herein, “vigorous exercise” is intended to include sufficient exercise to cause an individual to consume more energy than approximately 6 Metabolic Equivalent Tasks (MET). In a variation on this particular aspect, the first conductivity measurement can be performed terminally at the first height and the second conductivity measurement can be performed terminally at the second height. The first height may be substantially at the height of the subject's heart, or may be below the height of the subject's heart, and the second height may be above the subject's heart.

Another aspect of the invention relates to a method of assessing vascular health of an individual. The method includes maintaining a conductivity sensor adjacent the subject and performing a series of conductivity measurements of the subject. A series of conductivity measurements includes a plurality of conductivity measurements obtained over a period of time. The method further includes determining a transient habit of the subject's conductivity during the time interval using a series of conductivity measurements and evaluating the vascular health of the subject using the transient habit of the conductivity. As used herein, the term "transient behavior" of an individual's conductivity refers to the behavior or variation in the individual's conductivity over a period of time.

In a variant of this particular aspect of the invention, a series of conductivity measurements are performed when the distal end is elevated above the heart of the subject. In certain aspects of the invention, the plurality of conductivity measurements are performed at regular predetermined time intervals during the time period.

Another aspect of the invention relates to a conductivity sensor that continuously monitors the conductivity of an individual for a predetermined time period. The conductivity sensor includes an induction coil that performs conductivity measurements, and a controller configured to direct the conductivity sensor to perform a series of conductivity measurements. A series of conductivity measurements includes a plurality of conductivity measurements obtained over a period of time. The conductivity sensor also includes a housing. The housing may keep the conductivity sensor adjacent to the object while a series of conductivity measurements are performed.

In a variation of this particular aspect of the invention, the conductivity sensor may comprise a database configured to store a series of conductivity measurements. In certain aspects, the conductivity sensor can include a communication device for communicating a series of conductivity measurements to a remote device. In another particular aspect, the conductivity sensor may include an alarm system to trigger an alarm when one conductivity measurement of the plurality of conductivity measurements reaches a predetermined threshold.

In another variation of this particular aspect of the invention, the housing of the conductivity sensor is fixed to the distal end of the individual. For example, the conductivity sensor may include a strap for securing the conductivity sensor to the distal end of the individual. In another particular aspect, the conductivity sensor can be secured to the object with an adhesive material. In still other aspects, the conductivity sensor can be part of a medical sling used to support the distal end of the subject. In yet another aspect, the conductivity sensor can be part of a garment or uniform worn by law enforcement or military personnel.

Yet another aspect of the disclosure relates to a platform unit that measures the conductivity of an individual. The platform unit includes a base unit configured to support an object standing on the platform unit and an induction coil for performing conductivity measurements on the feet of the object standing on the platform unit. The platform unit can include a visual display configured to display the conductivity measurement on the object. In a variation of this particular aspect, the platform unit may comprise an induction coil for performing conductivity measurements of the feet of the individual standing on the platform unit.

These and other features, aspects, and advantages of the present invention will be better understood with reference to the following description and appended claims. Different combinations or configurations and equivalents of the features, steps, or components disclosed, as well as differently provided preferred embodiments of the present disclosure (features, parts not explicitly shown in the figures or described in the detailed description of these figures) Or a step, or a configuration thereof). Additional embodiments of the present disclosure that do not necessarily need to be described in summary are provided in the context of features, components, or steps referred to above, and / or referring to other features, components, or steps as discussed herein. Various combinations may be included. Those skilled in the art will appreciate the features and aspects of these embodiments better by examining the remainder of the specification.

DETAILED DESCRIPTION The disclosure of the present invention, including the best mode fully and practicable for those skilled in the art to which the present invention pertains, is described herein with reference to the following attached drawings:
1 shows a flow chart of exemplary steps associated with one exemplary embodiment of the present invention;
2 shows a flow chart of exemplary steps associated with another exemplary embodiment of the present invention;
3 shows a flowchart of exemplary steps associated with another exemplary embodiment of the present invention;
4 provides a block diagram of an exemplary conductivity sensor in accordance with one exemplary embodiment of the present invention;
5A shows a top view of an exemplary induction coil in accordance with one exemplary embodiment of the present invention;
FIG. 5B shows a top view of the exemplary induction coil shown in FIG. 5A, showing a second conductive coil arranged spirally inwards relative to the first conductive element; FIG.
6A shows an exemplary conductivity sensor held adjacent to the distal end of the subject according to one embodiment of the present invention;
FIG. 6B shows a top view of the example conductivity sensor shown in FIG. 6A;
7 illustrates an example platform unit, according to an example embodiment of the invention; And,
8-11 show data obtained during clinical study # 1 and clinical study # 2 discussed below.

In general, the present technology relates to methods and apparatus for using conductivity measurements to assess vascular health or to diagnose a vascular condition of an individual. For example, certain embodiments of the present technology can diagnose a peripheral artery, monitor a patient's warming, monitor circulatory shock, monitor a subject's blood flow, A method and apparatus for using conductivity measurements to determine if a person has venous or arterial occlusion, or to determine other vascular conditions or to assess vascular health of an individual.

Reference will now be made in detail to embodiments of the invention, in which one or more examples are shown in the drawings. Each example is provided by way of explanation of the invention, not limitation of the invention. In fact, it will be apparent to those skilled in the art that various modifications and variations can be made to the present invention without departing from the scope or spirit of the invention. For example, features illustrated and described as part of one embodiment may be used in conjunction with another embodiment, yielding another embodiment. Thus, it is intended that the present invention cover such modifications and variations as come within the scope of the appended claims and their equivalents.

Soft tissue just below the skin consists mainly of a two-phase medium of vascular tissue and interstitial fluid. Vascular tissue adjacent to the skin generally includes very small blood vessels, such as, for example, capillary, arterioles, venules. This vascular tissue portion of human tissue is considered to have a relatively low electrical conductivity. The low conductivity of the vascular tissue may be due to the insulating properties of the capillary walls and the tendency of nonconductive blood cells to increase the path to charge carriers. However, intercellular humoral conductivity has been evaluated to have significantly higher conductivity than that of capillaries. For example, some studies have evaluated the conductivity of intercellular fluids to be approximately 2.0 S / m.

If the capillary bed system's ability to contract or expand depends on the vessel wall and the stiffness of the adjacent tissue surrounding the vessel wall, the tissue conductivity is measured in response to altering the mechanical stress of the vessel. The technique should provide an efficient approach for the evaluation of vascular intensity. Any mechanical or physiological stimulus that can cause the volume fraction of vascular tissue to decrease can lead to increased conductivity of human tissue. Similarly, any mechanical or physiological stimulus, which can cause an increase in the volume fraction of vascular tissue, can cause the conductivity of human tissue to decrease.

The effect of vascular tissue volume on human tissue conductivity can be explained with reference to Archie's law. If the intercellular fluid has conductivity σ _b and volume fraction θ, the electrical conductivity of the soft tissue below the epithelium can be modeled by Arch's law as follows:

Here, a is, in most cases, a constant with no dimension whose value depends on various factors.

The intercellular volume fraction should be greater than the threshold θ _c to have sufficient percolation for non-zero conductivity. The vessel volume fraction is equal to 1-θ. If the intercellular volume fraction is sufficiently greater than the critical volume fraction, the electrical conductivity is expected to be sufficiently sensitive to slight fluctuations in the vascular tissue volume fraction.

There are natural situations that cause blood vessels to expand or contract. For example, capillaries at the extremities tend to contract when cooled, and have a net effect of lowering blood volume at the extremities. Thus, the measurement of conductivity at the end, which may be cold, must contribute to an increase in conductivity due to a decrease in volume occupied by the peripheral blood vessel image.

Another way to contract or expand the blood vessel image is to change the elevation of the tip to the heart. Height fluctuations change the nominal pressure of body fluids inside the blood vessels, causing the pressure to change as high or low as 40 mmHg. This is a significant portion of the normal phase blood pressure of approximately 120/80 mmHg. In healthy adults, fluctuations in height of the distal ends must result in blood pressure fluctuations that increase or decrease vascular tissue volume, each accompanied by a corresponding decrease or increase in conductivity.

The ability to detect fluctuations in the conductivity of human tissue due to volume fluctuations in vascular tissue volume will depend on the inherent elasticity of the vascular system. Healthy adults experience fluctuations in blood volume at their extremities due to the ability of their blood vessels to expand or contract in response to stimuli, which is a feature for properly controlling blood pressure. If the vascular system becomes diseased as in the case of atherosclerosis, the wall of the vessel becomes thick and stiff due to plaque deposits. The occurrence of atherosclerosis at the end is generally associated with peripheral arterial disease. Peripheral arterial disease is a vascular condition that affects one of three diabetic patients.

For individuals suffering from significant loss in vascular elasticity, the terminal's conductivity measurements performed while the terminal alternates up and down the heart, whether or not peripheral arterial disease or other conditions, provide the greatness of the condition. do. For example, a healthy adult should be expected to increase the conductivity in the forearm even after a short time when the forearm is elevated above the head. On the other hand, individuals suffering from vascular diseases that harden the vascular system can expect much less fluctuations in the electrical conductivity at their ends or no fluctuations when elevated above the head.

Another variable that tends to have an effect on the subject's conductivity is the subject's blood pressure. Individuals with higher blood pressure may have a greater volume of blood flowing through the vasculature, even if exposed to mechanical or physiological stress, which may tend to reduce blood volume at the distal end. Thus, blood pressure measurements used together with conductivity measurements in response to physiological and mechanical stimuli can provide an efficient tool for analyzing vascular health.

The effects of height fluctuations on human tissue conductivity measurements, as well as the relationship between human tissue conductivity and various other variables including both diastolic and systolic blood pressure, have been investigated in detail, and clinical studies # 1 and It is described below with reference to clinical study # 2.

With reference to FIG. 1, exemplary steps associated with a method 100 for determining a vascular state of an individual will be described. Step 110 of the method includes performing a first conductivity measurement of the distal end of the subject at the first height. As used herein, the term extremity may refer to the arm or leg of an individual. Reference to "upper body extremity" refers to an arm of an individual, and reference to "lower body extremity" refers to an individual's legs.

The conductivity measurement of step 110 may be performed using any device or device configured to measure the conductivity of the specimen. For example, conductivity measurements can be performed with conventional electrodes or various induction coil devices. One such conductivity sensor that may be used in accordance with the present technology is US Patent Application No. filed May 12, 2009, which is incorporated herein by reference. 12 / 464,431.

As shown in step 120, when the first conductivity measurement is performed, the method 100 includes elevating the distal end of the subject to a second height. At step 130, the method 100 includes performing a terminal second conductivity measurement at the second height. The second conductivity measurement can be performed after the distal end is elevated for a predetermined time period at the second height. For example, the second conductivity measurement can be performed after the distal end is elevated for a time interval of about 60 seconds, about 45 seconds, about 30 seconds, or about 120 seconds, or any other time interval at the second height. By elevating the distal end to the second height for a predetermined time interval before performing the second conductivity measurement, the subject's vasculature has sufficient time to respond to the stimulus provided by the height variation of the distal end.

Similar to the first conductivity measurement, the second conductivity measurement can be performed using any device or device configured to measure the conductivity of the fabric. Preferably, to ensure an accurate comparison of the first and second conductivity measurements, the device or device for performing the first conductivity measurement is the same as the device or device for performing the second conductivity measurement.

The first and second heights of the distal end can be any height that can be reached by the distal end, so long as the first and second heights differ to take advantage of vascular volume variation. In certain embodiments, the first height is substantially equal to or below the height of the subject's heart and the second height is above the subject's heart. In this way, the present technology can utilize a decrease in blood vessel volume caused by a decrease in blood pressure at the elevated end.

In certain embodiments, the first conductivity measurement may be performed while the arm of the subject is unfolded or rested at a position substantially equal to or below the height of the subject's heart, and the second conductivity measurement is lifted over the subject's head. The arm is lifted and performed. In another exemplary embodiment, the first conductivity measurement may be performed on the subject's legs while the subject is lying so that the subject's legs are substantially equal to or below the height of the subject's heart. The second conductivity measurement may be performed with the leg elevated above the subject's heart. For example, the second conductivity measurement can be performed when the leg of the individual is elevated in the medical sling.

In step 140, after performing the second conductivity measurement, the method of the present technology compares the first conductivity measurement with the second conductivity measurement to determine the conductivity displacement Δσ of the terminal in response to the height variation of the terminal. The conductivity displacement Δσ refers to the difference between the second conductivity measurement and the first conductivity measurement. As described in detail below, the conductivity displacement Δσ can be used to diagnose the vascular condition of an individual.

For example, in one embodiment, the conductivity displacement Δσ may be used to monitor the progression of peripheral arterial disease. As described in the discussion of Clinical Study # 1 and Clinical Study # 2, the conductivity displacement Δσ is proportional to vascular tissue flexibility. The conductivity displacement Δσ should be greater for individuals with healthy vascular tissue that is not rigid, for example, by the onset of peripheral arterial disease. Thus, because the conductivity displacement Δσ provides an indicator of vascular flexibility, the analysis of the conductivity displacement Δσ according to the present technology provides a useful tool for monitoring the progression of peripheral arterial disease in a subject. Other applications of the method may be used to monitor cooling of the patient, monitor the progress of circulatory shock, monitor blood flow or blood volume of the subject, and / or determine whether the subject has an arterial or venous obstruction of the vascular system. .

In a variation of this embodiment, the method 100 may further comprise taking a blood pressure measurement of the subject, as shown in step 150. Blood pressure measurement may include both systolic and diastolic blood pressure measurements performed by conventional methods known in the art. The method 100 may assess blood vessel status using blood pressure measurements in conjunction with the conductivity displacement Δσ of the subject, as shown in step 160. For example, as described in the discussion of clinical studies # 1 and clinical studies # 2, those with lower diastolic blood pressure should exhibit more pronounced conductivity displacement Δσ in response to distal height, The bearer should indicate little or no conductivity displacement Δσ.

As another example, the conductivity displacement Δσ may also be used in conjunction with blood pressure measurements to determine whether an individual has vein or arterial occlusion. For example, as discussed in Clinical Study # 2 below, any individual who exhibits hypertension and exhibits significant conductivity displacement Δσ is suspected of some degree of arterial occlusion.

2, another exemplary embodiment of the present invention will be described. As shown in step 210, the method 200 includes performing a first conductivity measurement of the subject. The conductivity measurement of step 210 can be performed using any device or device configured to measure the conductivity of the specimen.

After the conductivity measurement is performed, the method 200 includes causing the subject's vasculature to be stimulated. The stimulus can be any physiological or mechanical stimulus that causes a change in blood flow through the subject's vascular system. For example, in one embodiment, the stimulus may be elevating the distal end of the subject to a height above the subject's heart.

In certain embodiments, the step of causing the subject's vascular system to be stimulated is performed by causing the subject to actively exercise (step 220 of FIG. 2). As used herein, “vigorous exercise” is defined as including an exercise sufficient to cause an individual to consume more than approximately 6 Metabolic Equivalent Tasks (MET). The subject may be active by requiring the subject to perform aerobic exercise, for example, running, jogging, walking, cross training, cross country skiing, rowing, or any other activity that increases the subject's heart rate. Can be done. In certain embodiments, vigorous exercise is, for example, a treadmill, an elliptical machine, a rowing machine, a stationary bicycle, a stair climber, a nautilus equipment, or any It can be carried out in a variety of facilities, including other facilities.

After the subject's vasculature is stimulated, for example by subjecting the subject to vigorous movement, the method 200 includes step 230 of performing a second conductivity measurement of the subject. Similar to the first conductivity measurement, the second conductivity measurement can be performed using any device or device configured to measure the conductivity of the specimen. Preferably, to ensure an accurate comparison of the first and second conductivity measurements, the device or device for performing the first conductivity measurement is the same as the device or device for performing the second conductivity measurement.

At 240, after performing the second conductivity measurement, the method 200 compares the first conductivity measurement with the second conductivity measurement to determine the conductivity displacement Δσ of the subject in response to the stimulus. The conductivity displacement Δσ refers to the difference between the second conductivity measurement and the first conductivity measurement. In step 250, the conductivity displacement Δσ is used to evaluate the vascular system of the subject, in accordance with the teachings herein.

In many cases, it may be desirable to continuously monitor the conductivity of human tissue over a period of time to determine the transient behavior of the terminal conductance. Transient wetness of conductivity may be particularly useful in determining whether a patient or other subject is adequately warmed, circulating shock, or whether blood is properly flowing to the end of the subject. For example, if a person's conductivity suddenly increases to a certain level, this indicates that the vascular volume at the end has experienced a sudden decrease, indicating that the individual may be entering circulatory shock.

To address this concern, another embodiment of the present invention relates to a method of assessing vascular health. With reference to FIG. 3, exemplary steps associated with exemplary method 300 of the present invention will be described. In step 310, the method includes maintaining the conductivity sensor adjacent the object for a predetermined time period. Similar to the method 100 described in FIG. 1 and discussed herein, the conductivity sensor for the present example facility may be any device or device that measures terminal conductivity.

At 320, a series of conductivity measurements are performed at the end while the conductivity sensor is held adjacent to the subject. The series of conductivity measurements includes a plurality of conductivity measurements obtained during the time period. Multiple conductivity measurements may be taken at regular time intervals or at irregular time intervals depending on the programmed instructions. A series of conductivity measurements can be performed at the ends at any height. In certain embodiments, a series of conductivity measurements are performed at the distal end above the heart of the subject when the distal vascular tissue volume is particularly sensitive to mechanical or physiological stress.

At step 330, the method 300 according to the present exemplary embodiment uses a series of conductivity measurements to determine the transient behavior of conductivity for a predetermined time period. The transient behavior of conductivity can be used to monitor or assess the vascular health of the subject at step 340.

For example, in one embodiment, transient behavior can be used to monitor the warming of a patient. When the body temperature drops to dangerously low levels, blood circulation to the ends is reduced. As the patient warms, the blood volume returns to the distal end, resulting in a decrease in distal conductivity. Thus, analysis of the transient behavior of terminal conductivity can be useful for determining the effect of warming of a patient.

In another embodiment, transient behavior can be used to monitor the onset of circulatory shock in a subject. Circulatory shock is a condition in which insufficient blood flow reaches the body's tissues. During the onset of circulatory shock, conductivity measurements of body tissue will be expected to increase as less blood flows into the tissue. Thus, analysis of the transient behavior of terminal conductivity can be useful for monitoring the onset of circulatory shock.

Other applications of the technology may be in combat scenarios, legislative enforcement scenarios, or other scenarios where an individual may be at risk of injury resulting in blood loss. An individual may be required to wear a conductivity sensor as part of his or her uniform to monitor the individual's conductivity. When the conductivity reaches a predetermined threshold, the conductivity sensor can send an alert to the medical personnel alerting the person that he or she may just be entering a circulatory shock.

Other applications of the present technology may include probing intubation sites, probing surgical locations, monitoring circulation during medical procedures or recovery, or include various applications.

Conductivity measurement according to the method of the present technology can be performed with any apparatus or device for conductivity measurement. A block diagram of an example conductivity sensor 400 is provided in FIG. 4. As shown, the example conductivity sensor 400 may or may not be part of a reactive circuit 420, a control circuit 440 with a controller 430, a database system ( 450, communication device 460 and alert system 470.

Induction coil 410 may be configured to perform conductivity measurements by generating an electric field that generates an eddy current in the conductive sample. Sensor 400 is described in US Patent Application No. filed May 12, 2009, which is incorporated herein by reference. It may be configured to measure the conductivity of the specimen using the techniques described in detail in 12 / 464,431.

In certain embodiments, the conductivity sensor may perform conductivity measurements with a conductivity sensor having an induction coil that probes a human tissue specimen to a predetermined depth to prevent interference from bones and internal organs. For example, the induction coil may be configured to probe the distal end to approximately 15 mm below the subject's skin.

This exemplary induction coil is shown in FIG. 5A. Induction coil 10 may include conductive element 12 disposed on circuit board 15. The circuit board 15 may be a printed circuit board or any other board modified or configured to mechanically support the conductive element 12. The circuit board 15 supports the conductive element 12 on opposite first and second sides of the circuit board 15. The first side 14 of the circuit board 15 is shown in FIG. 5A.

As shown in FIG. 5B, the conductive element 12 includes a first conductive element 16 spiraling outwardly from the first side 14 of the circuit board 15 and a second side of the circuit board 15. In a spiral inwardly facing second conductive element 18. The second conductive elements 18 are arranged staggered inwardly in a spiral with respect to the first conductive element 16. In the embodiment shown in FIG. 5B, the first conductive element 16 spirals outwardly with an outer diameter, passes to the other side of the circuit board 150, and then internally spirally as the second conductive element 18. Heads up. The second conductive element 18 is staggered with respect to the first conductive element 16.

The probing depth of the induction sensor can be changed by varying the dimensions of the induction coil, or by adjusting the resonant frequency of the induction coil reactance circuit. For example, the outer diameter of the induction coil 10 may range from about 5 mm to 120 mm, such as about 10 mm to 80 mm, about 30 mm to 40 mm, about 35 mm, about 38 mm, or any other diameter or diameter. It can be a range. The inductance of the induction coil may be in the range of about 3 to 4 μH, such as about 3.2 to 3.6 μH, about 3.4, 3.5 μH, 3.5 μH or any other inductance or inductance range. The interwinding capacitance of the induction coil may be approximately 10 pF. The self resonance point of the induction coil may be approximately 27 MHz. In this particular embodiment, if additional parallel capacitance is added to adjust the resonant frequency to approximately 15 MHz, the electric field generated by the induction coil passes below a depth of approximately 15 mm to prevent interference from bone and internal organs. shall.

Referring again to FIG. 4, the induction coil 410 may be part of or coupled with the reactance circuit 420. In certain embodiments, reactance circuit 420 may include resistive elements, capacitive elements, and inductive coils connected in parallel. The conductivity sensor may have a control circuit 440 that drives the reactance circuit 320 such that the reactance circuit 320 resonates when the induction coil 410 is maintained adjacent to the object. This exemplary induction coil conductivity sensor is described in US Patent Application No. filed May 12, 2009, which is incorporated herein by reference. It is described in detail in 12 / 464,431.

Control circuitry 440 and controller 430 form the central processing and control circuitry of the exemplary conductivity sensor 400. Control circuit 440 includes a variety of devices that maintain the reactance circuit in resonance when the induction coil is placed adjacent to the specimen. The controller 430 is the main processing unit of the conductivity sensor 400. The controller 430 may be configured to instruct the conductivity sensor to perform a plurality of conductivity measurements at predetermined regular or irregular time intervals during the predetermined time period. In this way, the conductivity sensor 400 can be used to determine the transient effect of the conductivity of the sample by performing a series of conductivity measurements on the sample for a predetermined time period. This kind of conductivity sensor is particularly useful for monitoring the vascular health of an individual.

With continued reference to FIG. 4, the conductivity sensor 400 can include a database system 450 operatively coupled to the controller 430. Database system 450 may be configured to store conductivity measurements made by conductivity sensors for future use and analysis. For example, the conductivity sensor 400 may be instructed by the controller 430 to perform a series of conductivity measurements over a three hour time period at a rate of one conductivity measurement per second. In another example, conductivity sensor 400 may be instructed by controller 430 to perform a series of conductivity measurements for a 60 second time interval at a rate of one conductivity measurement every 10 ms. Those of ordinary skill in the art will appreciate that, using the teachings disclosed herein, the invention is not limited to any particular time interval or time interval between conductivity measurements. Database system 450 will store each of the conductivity measurements performed during that time interval so that the conductivity measurements can be later analyzed to determine transient effects.

With continued reference to FIG. 4, the conductivity sensor 400 can include a communication device 460 operably connected to the controller 430. Controller 430 can interact with communication device 460 to interface with various remote devices, such as remote laptop computers. For example, controllers can interact via Bluetooth® wireless communication modules to interface data collection and control applications with remote computers. The Bluetooth® wireless communication interface may be a Bluegiga WT12 Bluetooth® module that allows full duplex serial communication between the remote device and the controller 430. In addition, the controller 430 may communicate via one or more communication networks. It should be understood that a communication device or medium may include one or more networks of various forms. For example, the network may include a dial-in network, a local area network (LAN), a wide are network (WAN), a public switched telephone network (PSTN), the Internet, an intranet, or another type of network. have. The network may include any number of wired, wireless or other communication links and / or combinations thereof.

Still referring to FIG. 4, the controller 430 may be operatively coupled to the alert system 470. The alert system 470 may be configured to provide a visual or audio alert when the conductivity of the specimen reaches a predetermined threshold. For example, in certain embodiments, alarm system 470 may be configured to emit an LED device when the conductivity of the specimen reaches a predetermined threshold. In another embodiment, the sample may be configured to sound an acoustic alert when the conductivity of the sample reaches a predetermined threshold. In another embodiment, the alert system 470 can provide notification to a remote employee via the communication device 460 when the conductivity of the sample reaches a predetermined threshold.

The conductivity sensor according to the present technology can be packaged in various forms depending on the intended application of the conductivity sensor. For example, as shown in FIGS. 6A and 6B, the conductivity sensor 600 may be packaged into the compact housing 610. The term "compact housing" as used herein refers to any housing having a length of about 25 cm or less, such as about 15 cm or less, about 10 cm or less. Compact housing 610 includes a conductivity system including any database for storage of conductivity measurement data, a communication device for interfacing with a remote device, and an alarm system that provides an alarm when the conductivity measurement reaches a predetermined threshold. Stores all necessary electronics and circuitry for the operation of sensor 600.

The compact conductivity sensor 600 shown in FIG. 6A may be held adjacent to the object using any structure or material for attaching or securing the conductivity sensor 600 to the object. For example, as shown in FIG. 6A, the conductivity sensor 600 may include a strap 620 that is used to secure the conductivity sensor to the arm of the subject. In other embodiments, the conductivity sensor 600 may be maintained adjacent to the subject by the use of an adhesive material. Such adhesive materials may include medical grade skin adhesives such as 3M Double Coated Spunlace Nonwoven Tape 9917 manufactured by 3M and / or 3M Transfer Adhesive 1524 manufactured by 3M. By keeping the conductivity sensor 600 close to the subject, the conductivity sensor can perform a series of conductivity measurements on the specimen for a predetermined time period. The conductivity sensor 600 may be particularly useful for continuously monitoring the conductivity of the distal end of the subject to determine the transient effect of the subject's conductivity.

FIG. 6B shows a top view of the conductivity sensor 600 shown in FIG. 6A. As shown, the conductivity sensor 600 includes an induction coil 10 similar to the induction coil shown in FIGS. 5A and 5B. Housing 610 and strap 620 are used to continuously hold induction coil 10 adjacent the specimen to continuously monitor the conductivity of the specimen.

In another exemplary embodiment of the present invention, the conductivity sensor is used as part of a medical sling for evaluating the distal end of an individual. The sling includes a conductivity sensor 400 similar to that shown in FIG. 4 for continuously monitoring the terminal's conductivity. If the terminal conductivity reaches a predetermined threshold generated by, for example, a decrease in blood circulation at the terminal, the conductivity sensor may provide an indication or alarm indicating that the terminal conductivity has reached a predetermined threshold. Can be.

In another exemplary embodiment of the invention, the conductivity sensor may be included in a garment or uniform. Such conductivity sensors may be particularly useful in combat scenarios, regulatory enforcement scenarios, or other scenarios where an individual may be at risk of injury resulting in blood loss. The uniform or garment may include a conductivity sensor 400 similar to that shown in FIG. 4 for continuously monitoring the conductivity of the distal end. When the conductivity of an individual wearing clothing or a uniform reaches a predetermined threshold, the conductivity sensor may send an alert to the medical personnel warning that the person may just enter the circulatory shock.

Referring to FIG. 7, a platform unit 700 for measuring the conductivity of an individual is disclosed. The platform unit includes a base 710 configured to support an object standing on the platform unit 700. The base unit 710 includes a platform including any database for storing conductivity measurement data, a communication device for interfacing with a remote device, and an alarm system that provides an alert when the conductivity measurement reaches a predetermined threshold. It may include necessary electronic devices and circuits for the operation of the unit 700.

As shown, platform unit 700 includes two regions 730, 740 that receive a person's foot standing on platform unit 700. There is an induction coil 10 in regions 730 and 740. Induction coil 10 may be similar to induction coil 10 shown in FIGS. 5A and 5B. When a person stands on the platform unit 700, the induction coil 10 performs conductivity measurements of the person's feet. Conductivity measurements are displayed via visual display 750. In certain embodiments, the conductivity measurement may be stored in a database, communicated to a remote device, or used to trigger an alert when the conductivity measurement is above a predetermined threshold.

The platform unit 700 allows an individual to perform conductivity measurements periodically using a simple device similar to a common scale found in a person's home. An individual with vascular health problems can use platform unit 700 to periodically monitor the individual's vascular health from an individual's home facility.

Clinical study # 1

The first clinical study was conducted to measure the electrical conductivity of human tissue at various points in the human body in areas extending below the skin surface at a depth of approximately 15 mm to ultimately determine normal conductivity levels for healthy adults. In this study, 40 healthy adults aged 25 to 45 years were selected. This adult group included 16 adult men and 24 adult women. Conductivity measurements include (1) mid-volar forearm (M); (2) proximal volar forearm (P); (3) inner upper arm (U); (4) lumbrosacral (lower back) S; (5) internal middle thigh (T); (6) posterior calf (C); And (7) three times in seven positions on each side of the body, including the lower part of the foot (ball) F. The final measurement was repeated once, left on the head for 60 seconds, and then made on the middle forearm of the right arm.

Conductivity measurements are described in U.S. Patent Application No. filed May 12, 2009, which is incorporated herein by reference. This was done using a conductivity sensor of the kind described in detail in 12 / 464,431.

Each subject was asked to visit the entire clinic four times for a complete set of measurements. At the first visit to the clinic, it was marked with a surgical pen to facilitate repetition to the same location at the next visit and was also the same in one iteration to the next. The first two measurement sets measured four hours apart were also two weeks ahead of the third and fourth sets of four hour intervals. During the measurement, the subject could sit comfortably at the treatment table with his torso upright and his legs extended at the same height as the hips. Before collecting the measurement set, subjects were given 15 minutes to relax and adjust to their surroundings. The laboratory temperature was maintained at approximately 72 ° F. and the humidity was maintained at approximately 40%.

Subjects are considered to be healthy if they are non-smokers and are not too overweight (Body Mass Index below 27) and are not on medication periodically because of cardiovascular problems. In addition to conductivity measurements, the following were measured: weight, height, blood pressure (both arms), urine specific gravity, pulse rate, BMI, percent body water, percent body fat, and bone weight. Blood pressure in both arms was measured due to a known difference between the right and left sides due to vascular disease. In addition, the last menstrual date was recorded for age and for women. Table 1 provided below provides a summary of the data obtained during the study.

location Female Average Conductivity (S / m) Male Average Conductivity (S / m) L L-std R R-std L L-std R R-std M 3.82 0.36 3.74 0.39 3.4 .24 3.3 0.26 P 3.94 0.32 3.9 0.39 3.56 .26 3.53 0.23 U 4.04 0.46 3.84 0.4 3.7 .35 3.46 0.3 S 2.97 0.28 3.2 0.32 2.83 .17 3.01 0.31 T 3.99 0.36 3.66 0.29 3.43 .36 3.13 0.31 C 3.69 0.27 3.65 0.25 3.21 .27 3.17 0.24 F 3.55 0.41 3.75 0.5 3.49 .35 3.59 0.34 all: 3.71 0.35 3.68 0.36 3.37 .29 3.31 0.28

Table 1 summarizes the various means obtained by gender and location. As the data shows, the difference between the left and right points is small except for the internal thigh which is almost 10% higher for both male and female subjects at the left thigh point.

The main hypothesis of the study was that electrical conductivity should increase with decreasing vascular volume. In FIG. 8, matched pair test results are shown comparing the right arm elevated above the heart with the unelevated. As shown, the increased conductivity while lifting the right arm is generally observed in an average amount of 0.33 S / m for all subjects. The two high points in the figure were excluded from the analysis because they were obtained with the wrong technique. As the analysis indicates, there is a 95% chance that the conductivity displacement Δσ data will be in the range of 0.276 S / m to 0.384 S / m.

The remainder of Clinical Study # 1 was related to determining whether there was a relationship between conductivity and conductivity displacement Δσ, weight, height, blood pressure (both arms), urine specific gravity, pulse rate, BMI, percent body fat, percent body fat, and bone weight. The results of clinical study # 1 included the following: (1) Conductivity was nominally about 0.36 S / m higher for women than for men; (2) conductivity decreases with age at all body positions when the variables of all other subjects are fixed; (3) conductivity decreases with increasing systolic blood pressure when all other variables are fixed at all body points; (4) For most positions, the conductivity decreases steeply as the percentage body water increases.

Clinical study # 2

The second study was conducted to include a more extensive investigation of the role of terminal height in conductivity. The second clinical study allowed a wide array of subjects to include smokers and to cover a wide range of ages and body mass index (BMI). The selection of subjects was based on the desire to identify various patterns of conductivity displacement in healthy and unhealthy individuals, increasing the likelihood of encountering vascular health individuals with poor immune responses. Only male subjects were included because males are more likely to show signs of peripheral arterial disease.

Subjects included 39 subjects divided into six groups, in which group 1 was determined to be the healthiest group and group 6 was determined to be the least healthy group. The ranking was based on three factors: age, BMI and smoking. Smoking was quantified according to whether the subject smoked more than three cigarettes a day or no smoking for at least 10 years. Table 2 below shows the distribution of the groups and how they are ranked by risk.

DOE grid Non-smoker smoker Age range: 25-35 36-70 40-70 BMI <28 7 (1) 5 (2) 7 (5) BMI> = 28 5 (3) 7 (4) 8 (6) A total of 39 male subjects; 6 categories

Numeric group number provided in parentheses and the risk level assigned to the group, with 1 being the lowest and 6 being the highest.

Through further evaluation of the subject, additional risk factors were identified. This includes: high blood pressure (HBP); Asymmetric blood pressure (ABP); And diabetes. In general, subjects were found to have hypertension if the systolic pressure in both arms and two visits exceeded 120 mmHg. Subjects were considered to have asymmetry in blood pressure if the difference in mean systolic blood pressure between the left and right arms exceeded 5 mmHg. Studies have shown that peripheral arterial disease is considerably more common for those with asymmetric blood pressure. Subjects were considered to have diabetes if the information was voluntarily provided, and diabetes status was not validated. Four subjects became diabetic. The distribution of subjects across the six risk groups is shown in Table 3 below.

group Number of targets Target with HBP Target with ABP Target with HBP / ABP Group 1 7 One 4 0 Group 2 5 One One One Group 3 5 One 5 One Group 4 7 5 2 2 Group 5 7 4 One 0 Group 6 8 6 2 One

Efforts were made to have the same number of objects in each group, but this became impractical because of the last unseen effort to fill the empty spot. It can also be discussed that a BMI of less than 28 is not binding enough to be in Group 1, the “healthy group”. If overweight is a high incidence in the community, finding a subject with a BMI below 25 has proved difficult. The BMI breakdown for Group 1 was as follows: 21.5, 21.6, 25.1, 25.5, 26.1, 27.1, and 27.4

In addition to the electrical conductivity measurements, additional data was recorded for each subject, including: age, height, weight, blood pressure, pulse rate, urine specific gravity, BMI, bone weight, percent body fat, percent body fat, smoking in the left and right arms. , Conductivity measurement time. As can be expected these 15 "target variables" are not completely independent of each other. Principal component analysis (PCA) is needed to capture only about 6 of these subject variability.

Electrical conductivity measurements include (1) middle head forearm; (2) forearm head forearm; (3) inner upper arm; (4) lumbar spine; (5) internal medial thigh; (6) calf back; And (7) seven positions on each side of the body including the ball of the foot, a total of 14 first conductivity measurements were made. Each of these points was measured three times-all 14 points were visited in turn before repetition to the same point for repetition. Forearm measurements were obtained with the forearm in a suspended position. Subject was sitting at the treatment table with his back unsupported and his legs stretched approximately at the height of the hips.

Conductivity measurements are described in U.S. Patent Application No. filed May 12, 2009, which is incorporated herein by reference. This was done using a conductivity sensor of the kind described in detail in 12 / 464,431.

After all regular repeat experiments have been obtained, three measurements for the elevated end at the second height are made, and all repeat experiments are obtained simultaneously. This includes: a) elevated basement forearm of both left and right while in a seated position; b) elevated calf on both the left and right sides of the subject lying on their backs; c) calf during standing position. For each of the elevated positions, or for the standing position, the subject holds that position for 30 seconds before measuring electrical conductivity. While in the standing position, the subject was asked to equally distribute his weight on both feet. When measurements were made on one leg, the subject was asked to put his weight entirely on the other leg to relax the calf muscle being measured. Over the two weeks of clinic, room temperature was maintained at approximately 68 ° F. Prior to any conductivity measurement, subjects were waited in the laboratory for approximately 15 minutes to facilitate adaptation.

Before considering the height effect on the data obtained in clinical study # 2, the results of clinical study # 1 are considered first. In clinical study # 1 discussed above, the electrical conductivity in the right mid palmar forearm increased by a significant amount after 60 seconds of height in almost all subjects, regardless of male and female. 9 shows the effect on both genders and the change in conductivity is shown for subject number (each subject measured at four different times). If the conductivity standard deviation associated with conductivity measurements in the middle forearm is approximately 0.135 S / m (all gender, all subjects), then only one of the displacements can be clearly negative. Some of them may be somewhat negative because they are approximately one standard deviation of zero or less.

Although there are several data points in FIG. 9 indicating little or no variation, most represent positive conductivity displacements. To investigate the cause of the data distribution, the graph is repeated in FIG. 10 where all male subjects in clinical study # 1 showing hypertension (in either arm) are indicated by an upward triangle. Since only males participated in clinical study # 2, only males were included. The upward triangles represent data collected from high systolic blood pressure subjects. The downward facing triangles represent data collected from subjects with cardiac diastolic blood pressure of less than approximately 65 mmHg.

10 clearly shows that elevated systolic blood pressure is a major factor influencing the extent to which electrical conductivity rises (or does not rise) in response to height variations. It should be noted that only hypertensive individuals alone do not contribute to the data pool above the average conductivity displacement. It is also evident that low cardiac diastolic blood pressure in the right arm contributes to a more dramatic upward response to height fluctuations. Low cardiac diastolic blood pressure for clinical research purposes is defined as less than approximately 65 mmHg. Note that none of the subjects identified as having low cardiac diastolic blood pressure in the right arm exhibits negative electrical conductivity displacement Δσ. However, low or high blood pressure itself may not be the only factor influencing height-related conductivity displacement Δσ.

In addition, other parameters such as end temperature (not measured) and height are likely to play a role. The latter parameter can affect the amount of height variation possible for the subject, as well as any characteristic relaxation time for drainage (heavier individuals have more time to "drain"). May need).

The adjustment of storage volume in response to mechanical perturbations such as fluctuations in height and the effect of blood pressure and temperature on blood storage at the end is a complex problem. Nevertheless, the properties of FIGS. 9 and 10 are common for the health study group, even for individuals with somewhat elevated blood pressure. Those with low cardiac diastolic blood pressure should show a more noticeable increase in electrical conductivity in response to forearm height, and those with high cardiac systolic blood pressure should show little or no elevation.

In clinical study # 2, it was determined to reduce the lift time to 30 seconds, to partially prevent any discomfort for the subject, since individual measurements indicate that a shorter time may be tolerated. There was no initial determination of office temperature as the reduced temperature was only implemented for 2 days in clinical study # 2 trial. In addition, forearm measurements were performed at the base palm position rather than the middle palm position for ease of measurement. All three of these changes could have influenced the outcome of clinical study # 2.

FIG. 11 shows electrical conductivity displacement in the right basal palmar forearm in response to height fluctuations for clinical study # 2 after 30 seconds of elevation. The data was first sorted by smoking (1-48: non-smokers, 49-78: smokers) and then by age (subjects with the highest age are indicated as # 48 and # 78 in the graph). Having a high right arm systolic blood pressure was indicated by an upward triangle. Only one subject (from risk group 1) had right arm cardiac diastolic blood pressure below 65 mmHg (morning visit). His displacement during that visit was 0.22 ± 0.06 S / m, but during his second visit, when the cardiac diastolic blood pressure was 70, the conductivity displacement was negative -0.128 ± 0.06 S / m. Of the four subjects who reported diabetes, three had high blood pressure, but the other did not form a specific inherent pattern in this figure-one showed a strong negative displacement Δσ for two visits and the other Has a divided reading with one positive sound and one positive, the other two showing a moderately positive conductivity displacement Δσ for two visits.

Two features of FIG. 11 are very clear: (1) Hypertension does not necessarily lead to a weakened conductivity displacement Δσ as found in clinical study # 1; And (2) the negative conductivity displacement Δσ is entirely possible and statistically significant.

To solve the variability problem between FIGS. 10 and 11, the repeatability associated with conductivity displacement in the right base forearm is very low (~ 2.8%), suggesting that the uncertainty of the data is not a problem. Other possible problems include location and duration of measurement-(1) middle head forearm in clinical study # 2 but donor head forearm in clinical study # 2; (2) Wait time of 60 seconds in clinical study # 2 for 60 second wait time in clinical study # 1. If more than half of the measurements show a positive conductivity displacement Δσ, the waiting time will not seem to be too short. Since the conductivity at the base and intermediate positions is highly related to each other, choosing the base position rather than the intermediate position will not make any significant difference. Thus, the results of FIG. 11 with apparent variance are expected from a group of subjects who are mostly experiencing problems with certain vascular health.

Clearly, the major negative conductivity displacement Δσ and the larger variability itself occur mostly between older people and smokers (# 49- # 78). Comparing Figures 10 and 11, it would be reasonable to conclude that conductivity measurements are deeply affected by the state of vascular health. However, the determination of the state of vascular health through conductivity measurements is in proper collection and interpretation of the data.

In addition, clinical study # 2 produces a negative result of the conductivity displacement Δσ. To address this result, the following guidelines and scenarios have been proposed to be useful in the interpretation of conductivity displacement Δσ measurements in response to height variations:

(1) As a result of the increased limb height, unobstructed release of blood (from the small vein) from the vascular circuit occurs in the healthy vascular system. At the same time, less blood is supplied through the arteries to the capillaries, resulting in increased conductivity. This assumes no variation in intercellular fluid volume.

(2) As an inference to (1), less or no increase in conductivity should be expected when the systolic blood pressure is significantly increased, or increased conductivity displacement Δσ should be expected when the cardiac diastolic pressure is low.

(3) Only in the presence of arterial occlusion, the blood vessel image is difficult but still filling when the limbs are not elevated. When the limb is elevated above the heart, arterial occlusion interferes with normal peeling so that elevated conductivity in response to height is still observed, perhaps even when someone has high systolic blood pressure.

(4) If the discharge from the venous side of the vascular circuit is significantly worsened due to occlusion, even if the obstruction is not on the arterial side, the conductivity displacement is less noticeable or very low-suppose that intercellular fluid is not affected by height fluctuations.

(5) If the intracellular fluids enter the blood vessels or lymphatic vessels so that the blood volume does not change essentially in response to height, but the net discharge of intercellular fluids occurs to a significant extent, the conductivity displacement should be negative, perhaps much steeper. . This is an abnormal problem when blood vessels become significantly permeable and pressure differences cause the intercellular fluids to move easily into or out of capillaries, veins and lymphatic vessels. Alternatively, strong negative conductivity displacements can be predicted when intercellular body fluids cannot be supplied fast enough to follow the discharge.

(6) In general, with various abnormal conditions present in the peripheral vascular system, any combination of the above scenarios can exist, which results in a complex response of conductivity to mechanical perturbation such as height fluctuations.

As described in the guidelines above, if the wide range of possible scenarios that can occur, the distribution of the data observed in FIG. 11 may not be surprising, but a strong indication of a complex array of vascular health is in clinical studies # 2. Raise that similarity exists in the audience participating in. The somewhat obvious pattern shape should be expected only in the participants' much more carefully managed choices, as in clinical study # 1. Thus, many data points in FIG. 11 may be considered abnormal. In particular, looking at guideline 3, it can be fully discussed that everyone with high blood pressure and high conductivity displacement Δσ is suspected of some degree of arterial occlusion. In addition, if the draining problem described in the guideline 5 prevents the replacement of intercellular fluids at a rate sufficient to allow the arterial occlusion to follow the draining, then all subjects with a strong negative conductivity displacement Δσ are also suspected of the disease. .

For elevated calf conductivity measurements, each subject was asked to lie flat on his back while seated at the treatment table. From that position, the nurse kept his right or left leg at an angle of approximately 60 degrees from horizontal. After 30 seconds, electrical conductivity measurements were made. The data obtained indicate that the calf electrical conductivity represents an exceptionally large conductivity displacement Δσ in response to the height. In all cases, the conductivity displacement is positive.

Although conductivity measurements were not performed on the elevated leg in clinical study # 1, the proposed guidelines to explain the trend for elevated right forearm conductivity from clinical study # 1 are still elevated calf obtained in clinical study # 2. Interpretation of the data was applied. General observations of the data obtained during clinical study # 2 included: a) essentially the same average upward conductivity displacement was found for the legs (approximately 1.25 S / m); b) all displacements are positive; c) panel members, as large as 6 inches, exhibit the least displacement of all members of group 1 (correct for both legs); d) the variation between visits can be extreme (1.7 S / m; standard deviation for both points is approximately 0.075 S / m); e) 22 data points associated with hypertensive subjects are above the 95% confidence interval for the left calf, 10 data points below, 18 data points above the 95% confidence interval for the right calf and 12 data points Beneath it.

Applying the aforementioned guidelines, the data in clinical study # 2 support the conclusion that all subjects with hypertension and above-average electrical conductivity displacements must have a certain level of arterial occlusion. This assessment appears to be entirely consistent with the comparison of the ratio of what is considered normal to abnormal for different categories. Working with the left calf data, the normal: abnormal ratio for risk group 1 is 6.0 (6.0: 1) and 1.31 (1.31: 1) for all nonsmokers. Overall, left calf data gives the same ratio as 2.25 (2.25; 1). Interestingly, the same two subjects from risk group 1 that contribute to the group's "unhealthy" data for the left calf contribute to that group's unhealthy calf data. In individuals over 50 years of age or smoking (individual number> 35), a survey of the data obtained reveals that most have hypertension and also have a conductivity shift Δσ above average. This is not correct for subjects who are under 50 years of age and who do not smoke (subject number ≤ 35).

Analysis of the data obtained in Clinical Study # 1 and Clinical Study # 2 convincingly indicates that conductivity measurements are sensitive to the relative volume of intercellular fluids and vascular tissues. The effect of height on conductivity and the role of pressure in both the systolic and diastolic roles on the degree of conductivity displacement in response to height fluctuations is particularly convincing.

The normal prediction is that the electrical conductivity should increase in response to the increased height of the ends. Because the limbs are elevated, the blood exits the vein more easily, but the difficulty increases in entering and filling the capillaries through the arteries. Therefore, the electrical conductivity must increase in response to the reduced volume of the microvascular system. However, a decrease in conductivity is also possible in response to limb height, because it is so measured. The reduction in conductivity will depend on a wide variety of factors, including obstructions that may exist at various locations along the vascular circuit and the extent to which intercellular fluids themselves may tend to exit the measuring point through the microvascular system. As the conductivity sensor is placed firmly against the skin, the discharge of intercellular fluid can occur due to the pressure applied at that point. Instead, if the subject has a combination of significant vein occlusion, elevated blood pressure, and a wide range of opportunities for intracellular discharge through the microvascular system, the electrical conductivity may plummet in response to the terminal height. This was observed in subjects with higher risk who participated in clinical study # 2.

Conductivity displacement measurements in response to height fluctuations have been shown to be particularly efficient in identifying those suspected of deteriorating vascular function. As shown for healthy subjects in clinical study # 1, subjects with hypertension should show sub-average conductivity shifts for the subject group. Clinical study # 2 showed that subjects with various risk factors were much more likely to violate this criterion than subjects in the low risk group. In particular, smokers with hypertension were more likely to show conductivity displacement above the group mean. This is the result of occlusion at the arterial side of the vascular circuit and prevents the development of normal levels of blood volume that can be expected from hypertensive individuals.

When focusing only on non-elevated conductivity measurements at the upper end, various analytical methods show that subjects with known health risks exhibit electrical conductivity outside the established criteria for subjects with much lower risk. In particular, a smoker has a much lower conductivity than he should have at the point at the top end. As shown in clinical study # 1 without exception for all test points, the conductivity at each body point decreases with increasing age. Thus, conductivity measurements show that smoking has the same effect as aging.

Other successful strategies for using electrical conductivity data have included identification of conductivity outliers at all body positions and determining their distribution for various established risk groups. Although outliers are progressively more likely to be found in risk groups 1 to 4, less than expected was found in risk groups 5 and 6. Since data outliers obtained from subjects with both hypertension and asymmetric blood pressure states are similarly distributed, outlier distribution analysis may be effective to identify specific combinations of blood pressure abnormalities and those with signs. For example, the importance of blood pressure imbalance has been noted in the report as a potential marker for peripheral vascular disease.

The unexpected result in clinical study # 2 was the rather high electrical conductivity observed in the feet of most subjects. During the measurement, the nurse noted that most of the subjects had cold feet while keeping the subject in place for conductivity measurements. The laboratory temperature was 68 ° F, which is 4 ° F lower than during clinical study # 1. Although not planned at the outset, this deficiency results in providing reduced evidence that the blood volume fraction at the distal end is lowered, and consequently providing additional evidence, meaning higher conductivity. Cooler environments are expected to produce a certain decrease in blood flow to the extremities, particularly to the furthest away from the heart.

Ideally, electrical conductivity can be measured in the elevated limbs as a function of time, resulting in a capture of transient behavior for time intervals that probably last up to two minutes or more. The literature value for flow rate in a given vein is approximately 1.0 cm / sec and the flow rate in capillaries is reported to be approximately 0.5 cm / sec. If the distance the blood has to travel to see the effect related to a given height on electrical conductivity is approximately 30 cm, the nominal "relaxation time" will be in the range of approximately 30 to 60 seconds. Of course, the actual relaxation time will depend on various factors including the temperature at the distal end and the degree of muscle relaxation. If higher blood pressure maintains blood volume and blood pressure in Clinical Study # 2 becomes significantly higher, 30 seconds may be too short-only one subject had a right arm diastolic blood pressure below 65 mmHg. In the case of measurements in the calf while in the standing position, the problem of insufficient "setting" time becomes prominent because the calf muscles relax for approximately 3 seconds or less. In addition to relaxation resulting from height fluctuations and muscle tension, there are also relaxation processes associated with the contact pressure between the conductivity sensor and the skin.

Although the subject matter has been described in detail with reference to specific exemplary embodiments and methods thereof, those skilled in the art will recognize variations and modifications to these embodiments as they achieve an understanding of the foregoing. It will be appreciated that water and equivalents can be readily made. Accordingly, the scope of the present invention is not by way of limitation, but by way of example, and as will be apparent to one of ordinary skill in the art, the invention is intended to cover such modifications, variations and / or additions to the invention. Does not exclude inclusion

Claims (15)

In the method of determining the state of blood vessels of an individual,
Performing a first conductivity measurement of the distal end of the subject;
Causing the vascular system to be stimulated;
Performing a second conductivity measurement of the distal end of the subject; And
Comparing the first conductivity measurement to the second conductivity measurement to determine a conductivity displacement of the distal end in response to the stimulus
Including,
How to determine the state of blood vessels in an individual.
The method of claim 1,
Causing the vasculature to be stimulated includes elevating the distal end of the individual,
How to determine the state of blood vessels in an individual.
The method according to claim 1 or 2,
The step of causing the vascular system to be stimulated includes the step of causing the subject to exercise,
How to determine the state of blood vessels in an individual.
4. The method according to any one of claims 1 to 3,
Wherein the first conductivity measurement is performed when the distal end is at the first height, and the second conductivity measurement is performed when the distal end is at the second height,
How to determine the state of blood vessels in an individual.
The method of claim 4, wherein
The first height is substantially at the height of the heart of the subject, or below the height of the heart of the subject, and the second height is above the heart of the subject,
How to determine the state of blood vessels in an individual.
The method according to any one of claims 1 to 5,
Wherein the first and second conductivity measurements are performed with a conductivity sensor comprising an induction coil,
How to determine the state of blood vessels in an individual.
The method of claim 6,
The conductivity sensor is configured to probe the distal end to a depth of up to approximately 15 mm below the subject's skin,
How to determine the state of blood vessels in an individual.
The method according to claim 6 or 7,
The induction coil,
A first conductive element spirally outwardly around the outside; And
A second conductive element operatively connected to the first conductive element, the second conductive element alternately oriented inward spirally around the outside with respect to the first conductive element
Including,
How to determine the state of blood vessels in an individual.
The method according to any one of claims 1 to 8,
Performing a terminal blood pressure measurement; And
Determining a blood vessel state of the subject by using the blood pressure measurement together with the conductivity displacement
Further comprising,
How to determine the state of blood vessels in an individual.
The method according to any one of claims 1 to 9,
Determining whether the subject has peripheral arterial disease using the conductivity displacement;
How to determine the state of blood vessels in an individual.
The method according to any one of claims 1 to 10,
Monitoring the warming of the patient using the conductivity displacement;
How to determine the state of blood vessels in an individual.
The method according to any one of claims 1 to 11,
Monitoring the circulatory system shock using the conductivity displacement;
How to determine the state of blood vessels in an individual.
The method according to any one of claims 1 to 12,
Determining whether the subject has venous or arterial occlusion using the conductivity displacement;
How to determine the state of blood vessels in an individual.
In the method of evaluating the vascular health of an individual,
Maintaining a conductivity sensor adjacent to the object for a predetermined time period;
Performing a series of conductivity measurements on the subject comprising a plurality of conductivity measurements obtained during the time period;
Determining transient behavior of the subject's conductivity during the time period using the series of conductivity measurements; And
Evaluating vascular health of the subject using the transient behavior of the conductivity
Including,
How to assess vascular health of an individual.
The method of claim 14,
Performing each of the plurality of conductivity measurements in the series of conductivity measurements at predetermined regular time intervals during the time interval,
How to assess vascular health of an individual.

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